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Calculate the formula

Problem Description
You just need to calculate the sum of the formula: 1^2+3^2+5^2+……+ n ^2.
 
Input
In each case, there is an odd positive integer n.
 
Output
Print the sum. Make sure the sum will not exceed 2^31-1
 
Sample Input
3
 
Sample Output
10
 
用普通的做法会超时,只能用公式算n*(4*n*n-1)/3(其中n为第几个数),还有题目明明说好结果在int范围内的,但是必须用__int64才能过,郁闷。。。
 
 1 #include <stdio.h> 2  3 int main(){ 4     __int64 number; 5     __int64 n; 6     __int64 result; 7  8     while(scanf("%I64d",&number)!=EOF){ 9         n=(number+1)/2;10 11         result=n*(4*n*n-1)/3;12         printf("%I64d\n",result);13 14     }15     return 0;16 }

 

 
 

 

Calculate the formula